Apparatus and method for stabilizing pelvic ring disruption

ABSTRACT

A pelvic sling device is provided for reducing a fractured pelvis. The device includes a belt member and a buckle component that automatically locks at an optimal predetermined tension level to provide distributed hoop-like compression and reduction for a fractured pelvis.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is a divisional patent application from U.S.patent application Ser. No. 09/639,544 filed Aug. 16, 2000 titled“Apparatus and Method for Stabilizing Pelvic Ring Disruption” whichapplication claims priority from U.S. Provisional Patent ApplicationSerial No. 60/183,623, filed Feb. 18, 2000, and are both herebyincorporated by reference.

FIELD OF THE INVENTION

[0002] The invention relates to emergency treatment of a fracturedpelvis. In particular, the invention provides a non-invasive slingdevice for reducing a fractured pelvis in a manner that minimizesinternal bleeding.

BACKGROUND OF THE INVENTION

[0003] Many people die from internal bleeding due to a fractured pelvis.Achieving rapid hemodynamic stability in patients who have a fracturedpelvis decreases the mortality rate substantially. Unfortunately,currently there is no satisfactory method or device that may readily beutilized to stabilize a fractured pelvis in emergency situations outsidea hospital. Pelvic stabilization at an emergency site within the firsthour after the fracture occurs is critical and may often determinewhether the patient lives or dies.

[0004] Reduction and stabilization of the pelvis is thought to be themost effective means to control bleeding for the following reasons.First, it decreases fracture fragment motion to prevent dislodgment ofhemostatic clots and further tissue damage. Second, fracture reductionreopposes bleeding osseous surfaces, thus decreasing blood loss. Third,reduction decreases pelvic volume, thereby tamponading hemorrhage fromthe fracture and retroperitoneal tissue. Despite these widely recognizedbenefits, no adequate pelvic stabilization device for early managementof pelvic fractures is currently available.

[0005] The current standard of care for treating pelvic trauma consistsof fluid resuscitation, including appropriate use of blood products,angiography if necessary, and early invasive or non-invasive pelvicstabilization. Non-invasive pelvic stabilization techniques have beenused. For example, a sheet may be wrapped around the pelvis and tied.Alternatively, a vacuum-type splinting device, or a pneumatic anti-shockgarment may be used. These non-invasive techniques have a number ofsignificant problems. One problem is that successful use and applicationof the device is quite dependent on the emergency caregiver. The personapplying the device may not know how much compressive force to applycircumferentially around the pelvis. If too much force is applied, thenthe pelvis may be overly compressed causing significant complications.On the other hand, insufficient compressive force may leave thefractured pelvis unreduced, and therefore fail to adequately controlinternal bleeding.

[0006] Another problem with non-invasive pelvic stabilization devicesthat are currently used is that they typically prohibit or restrictvital access to the abdomen, perineum, and lower extremity. Furthermore,prolonged application of devices such as the pneumatic anti-shockgarment has been associated with significant complications, such ascompartment syndrome of the lower limbs.

[0007] Invasive pelvic stabilization methods utilize external fixation,pelvic C-clamps, and open reduction and subsequent internal fixation.External fixation devices can effectively reduce and stabilize thepelvis and are relatively simple to apply. However, their utility islimited most commonly to the operating room setting. The invasive pelvicstabilization methods generally are not appropriate for application atan emergency scene where unstable pelvic ring disruptions require rapidpelvic reduction and temporary stabilization.

[0008] Open reduction and internal fixation is the ultimate form oftreatment for a fractured pelvis, and is considered the gold standardfor accuracy of reduction, protection of neurovascular structures, andrigidity of fixation. However, its invasive nature makes itinappropriate for use in an emergency situation, such as the scene of acar accident, on the side of a mountain, or at a remote location of atraumatic fall.

[0009] Accordingly, an object of the invention is to provide a methodand apparatus for pelvic reduction and stabilization that isnon-invasive.

[0010] Another object is to provide a method and apparatus for pelvicreduction and stabilization that is capable of even and incrementalapplication of hoop stress to both hemi-pelves while avoiding reactiveforces that potentially can decrease the quality of reduction.

[0011] Another object of the invention is to provide a method andapparatus for pelvic reduction and stabilization that applies andmaintains hoop stress around the pelvis at a preset and safe level,while avoiding the application of excessive hoop stress.

[0012] A further object of the invention is to provide a method andapparatus for stabilization of a fractured pelvis that can be applied ina rapid and simple manner by a single person without extensive training.

[0013] Still another object of the invention is to provide a method andapparatus for stabilizing a fractured pelvis that can be applied at anemergency site without the need for additional complex or heavyequipment.

[0014] Another object of the invention is to provide a method andapparatus for stabilizing a fractured hip in a nonintrusive manner,while allowing vital access to conduct other important emergencyprocedures on the patient.

[0015] Another object of the invention is to provide a method andapparatus that permits stable pelvic reduction prior to and during theapplication of a pelvic external fixator in the clinical setting.

SUMMARY OF THE INVENTION

[0016] The invention provides beneficial methods and apparatus forstabilizing a fractured pelvis in an emergency setting without requiringuse of complex or invasive equipment. The invention may be used andcarried out by a single person without extensive training or expertise.

[0017] The invention provides a sling device for stabilizing a fracturedpelvis. A buckle is connected to a strap member to form a closed loop.The buckle has at least one automatic locking mechanism that allows thestrap member to be tightened around a fractured pelvis until apredetermined threshold force is reached. The closed loop then maintainsa substantially constant circumference until the strap member isreleased from the buckle.

[0018] The invention also provides a sling device including a beltmember with two end portions. A buckle has two substantially identicalbelt-engaging mechanisms. Each belt engaging mechanism is configured toreceive an end portion of the belt member so that the belt member can betightened symmetrically around a person's pelvis by pulling on the endportions of the belt member simultaneously.

[0019] In a preferred embodiment of the invention, the belt member issecured with a buckle including at least one rotating cylinder. Therotating cylinder has an outer surface that contacts a portion of thebelt member that at least partially wraps around the cylinder. The beltportion frictionally grips the outer surface of the cylinder so thatwhen rotation of the cylinder is locked, the belt member is preventedfrom slipping over the outer surface of the immobilized cylinder.

[0020] The invention also provides a method of stabilizing a fracturedpelvis. First, a belt is secured around a person's fractured pelvis. Thetension of the belt is then automatically set at a level that has beenpredetermined to substantially reduce a fracture pelvis withoutexcessive compression. In a preferred embodiment of the invention, thetension level of the belt is automatically set in the range ofapproximately 150 N to 250 N.

[0021] The invention also includes a method of securing a pelvic fixatorin an emergency situation. The fractured pelvis is first temporarilystabilized by tightening a belt device around the pelvis. A pelvicfixator may subsequently be applied while the belt is secured around theperson's pelvis.

BRIEF DESCRIPTION OF THE FIGURES

[0022]FIG. 1 is a front view of the pelvic ring.

[0023]FIGS. 2A and 2B are front views of unstable pelvic ringdisruptions.

[0024]FIG. 3 is a top view of a pelvic sling device according to apreferred embodiment of the invention.

[0025]FIG. 4 is a front view of a pelvic sling applied to a fracturedhip.

[0026]FIG. 5 is a side view of the sling and hipbone structure shown inFIG. 4.

[0027]FIG. 6 is a perspective view of a buckle for use on a pelvicsling.

[0028]FIG. 7 is a partial front view of a sling showing one end portionof the sling engaging the buckle of FIG. 6.

[0029] FIGS. 8-10 are cross-sectional views of the sling shown in FIG.7, illustrating a preferred mechanism for locking the tension of thebelt.

[0030]FIG. 11 is a partial cross-sectional view of the buckle shown inFIG. 6.

[0031]FIG. 12 is a graph illustrating the amount of tension required toreduce a fractured pelvis when the sling is applied at differentlocations.

[0032]FIG. 13 is a bar graph illustrating the results of an experimentto determine the amount of sling tension required to adequately reducethe symphysis gap in a fractured pelvis.

[0033]FIG. 14 is a set of four CT images showing a fractured pelvisbefore and after sling-induced reduction.

DESCRIPTION OF THE INVENTION

[0034] The invention includes many aspects that may be employedadvantageously to stabilize a fractured pelvis in an emergencysituation. Generally, the invention employs a compressive device thatcan be easily applied to a patient to provide an appropriate level ofhoop stress so that the fractured pelvis is reduced but not overlycompressed. Preferred examples and embodiments of the invention aredescribed below with reference to the figures.

[0035]FIG. 1 shows the bone structure that is referred to as the pelvicring 10. The pelvic ring is formed by the sacrum 12, ilium 14,acetabulum 15, ischium 16, pubic rami 17, and symphysis pubis 18.Anteriorly, pelvic ring 10 contains a fibro cartilage joint.Posteriorly, the pelvic ring 10 contains the sacroiliac joints 20, whichconnect the sacrum 12 with the left and right ilium.

[0036] Unstable pelvic ring disruptions are usually manifested by two ormore fracture sites. In an “open book” fracture, as shown in FIG. 2A,pelvic ring disruption is evident at symphysis pubis 18 and at one orboth sacroiliac joints 20. FIG. 2B illustrates a lateral compressionfracture in which pelvic ring disruption occurs at pubic rami 17 and atsacroiliac joint 20.

[0037]FIG. 3 shows a top view of a sling 30 including a belt member 32operatively combined with buckle device 34. Belt member 32 is comprisedof two overlapping lateral portions 36 a and 36 b. Belt portions 36 aand 36 b have a variably overlapping region 38 for making grossadjustments to the circumference of the sling so that one sling devicecan be used on people of different sizes. Any appropriate mechanism maybe used to provide variable overlap fixation of lateral belt portions 36a and 36 b, for example, hook and loop type fasteners, for example,VELCRO™, may be utilized in overlapping region 38.

[0038]FIG. 4 is a front view of a pelvic sling shown in operativeassociation with a human pelvis. FIG. 5 shows a side view of the samesling and pelvis of FIG. 4. Pelvic sling 50 has a belt portion 51including an approximately 6-inch wide posterior sling component 52.Posterior sling component 52 is situated behind sacrum 12 with its loweredge located at the level of the superior rim 54 of symphysis pubis 18.Posterior sling component 52 is preferably made of a radiolucentmaterial that is cushioned toward the skin interface to ensure a highdegree of pressure distribution. The material is of sufficient stiffnessto transmit tensile forces of at least 200 N without exhibiting strainlarger than 10%. The material also has sufficient inherent elasticity toconform in part to body geometry. Posterior sling component 52 extendslaterally toward the anterior portion of the abdomen. Symmetrical slingextensions 56 a and 56 b gradually decrease in width to approximately2-inches as they circumvent the sides of the pelvis. The centerline ofsling extensions 56 a and 56 b is approximately 2-inches above the loweredge of posterior sling component 52. Sling extensions 56 a and 56 b aredirected through buckle 58 which is centered over the abdomen. Buckle 58reverses the direction of both sling extensions 56 a and 56 b.Simultaneous application of sideward direct tensile force to each slingextension 56 a and 56 b yields in tensioning of the entire sling, whichin turn induces even hoop stress around the pelvis. The hoop-stresssubsequently reduces the geometric integrity of the disrupted pelvicring and promotes stability of the fracture fragments. After applicationof sling tension at the appropriate level, the ends of sling extensions56 a and 56 b are attached to lateral sling portions, for example, byhook and loop fasteners, to maintain sling tension.

[0039]FIG. 6 shows a perspective view of a preferred buckle design foruse on a pelvic sling. Buckle 80 is characterized by side-to-sidesymmetry relative to axis AA. Each of lateral buckle portions 82 a and82 b is designed to engage and secure an end of sling extensions 56 aand 56 b, respectively, at an appropriate tension level. The detailsdescribed below in relation to lateral buckle portions 82 b are the samefor lateral buckle portion 82 a, unless expressly distinguished.

[0040] Lateral buckle portion 82 b includes rotating cylinder 84 that isfree to rotate when buckle 80 is unlocked. As shown in FIG. 7, slingextension 56 b wraps around cylinder 84. Cylinder 84 rotates indirection 86 when the sling is being tightened. Holes 88 are provided incylinder 84, as shown in FIG. 6, for engaging a pin to lock rotation ofcylinder 84 as described in more detail. Gap 90 is defined betweencylinder 84 and side bar 92. Gap 90 is maintained by springs that arenot shown in FIG. 11. As belt tension increases, cylinder 84 is pulledtoward side bar 92, thereby decreasing gap 90. Eventually, a pin memberextending from side bar 92 engages hole 88 in cylinder 84, causingrotation of cylinder 84 to lock. The surface of cylinder 84 is devisedto frictionally hold and resist slipping of the belt material aroundcylinder 84 when rotation is locked.

[0041] Buckle 80 is preferably comprised of reliable and robust designcomponents to enable reproducible sling application to a preset and safetension level. Sling extensions 56 a and 56 b are inserted throughcenter portion 94 of buckle 80 and reverted by means of cylinders 84.Cylinders 84 have a rough outer surface to provide a high frictioninterface for engaging sling extensions 56 a and 56 b. Cylinder 84rotates with low friction on a polyethylene roller core (not shown). Theroller cores can slide laterally on parallel guide rods 100. FIGS. 8-10show cross-sectional views through the sling of FIG. 7, illustrating themechanism for locking rotational movement of cylinder 84. Lateraltranslation of cylinder 84 on guide rod 100 in direction 102 causes lockpin 104 to engage holes 88 in cylinder 84, disabling further rotation ofcylinder 84. This in turn disables further sling tensioning due to thehigh friction interface between sling extension 56 b and the outersurface of cylinder 84. This feature of the sling device automaticallyand reproducibly sets the tension of the sling at a predetermined level.The preset tensioning level is in the range of 150 N to 250 N,preferably 200 N.

[0042] Once the sling tension level is reached, lock pin 104 engageshole 88 on cylinder 84 and enters a second sinkhole of bigger diameterin cylinder 84. Lock pin 104 has a widened tip portion that engages theinner lumen of cylinder 84. Thus, even if the applied sling tensionsdecrease somewhat, cylinder 84 is not able to slide off lock pin 104,since cylinder 84 will impinge the widened tip portion of lock pin 104.Only if the applied sling tension decreases substantially will cylinder84 be pushed off lock pin 104 by means of compression springsillustrated in FIG. 11. This design feature, referred to as “lockinghysteresis,” makes it possible to maintain the preset sling tension,even if the applied tension to the sling extensions decreases. Anemergency technician can affix the ends of sling extensions 56 a and 56b to the lateral sling portions without the need to maintain full slingtension for a prolonged amount of time, and without losing the presetsling tension.

[0043]FIG. 11 shows another cross-section through buckle 80 of FIG. 7.Compression spring 110 counteracts lateral translation of cylinder 84along guidepost 100. Compression spring 110 is mounted over guide rod100, between side bar 92 and cylinder 84, and is covered by spring cage112. This design component allows guided lateral translation of cylinder84 against a pair of compression springs 110, only one of which is shownin FIG. 11. Collar 114 is located on the center region of guidepost 100.Collar 114 can plant rigidly to any site on guidepost 100 via screws.Collar 114 is used to hold each cylinder 84 in a laterally translatedposition, at which spring 110 is compressed to a preset value, forexample 75 N for each compression spring. Therefore, cylinder 84 willmaintain its position during sling tensioning up to the preset forcevalue, while sling extensions 56 a and 56 b are pulled over therespective rotating cylinders. Only if the sling tension exceeds thepreset value, will lateral translation of cylinder 84 be induced.

[0044] The sling buckle described above is fully symmetric, enablingsling buckle application in any orientation, therefore minimizingpotential complications in its application. The sling buckle componentsare preferably designed to be fabricated from non-metallic, radiolucentmaterials, excluding the cylinders, lock pins, and compression springs.This enables radiographic examination while maintaining pelvic reductionand stabilization.

[0045] The sling design constitutes two distinct components, the slingand the sling buckle, which are combined in a functional unit withminimal effort. Different size-specific slings may be used with the samebuckle. Furthermore, it may be desirable to provide a sling device inwhich the belt component is disposable and the buckle is reusable.

Sling Location

[0046] An optimal sling location has been found to be within atransverse plane at the level of the greater trochanteric region, justproximal of the pubis symphysis. Application of a sling further distallyis not feasible from a clinical perspective, disabling vital access torectal and genital regions and the femoral artery. Application of asling further proximally results in a significant decrease in the amountand quality of pelvic reduction corresponding to constant amounts ofsling tension. FIG. 12 is a bar graph showing the results of anexperiment to determine which sling location required the least slingtension to achieve pelvic reduction in different fracture scenarios. Thegraph shows that distal sling application, i.e., at the level of theacetabulum, required the least sling tension to achieve pelvic reductionin each of four different fracture scenarios: partially stable,unstable, partially stable and hemorrhaging, unstable and hemorrhaging.

Sling Tension

[0047]FIG. 13 shows a bar graph illustrating the results of anexperiment to determine the relationship between sling tension andsymphysis gap reduction. A sling tension level of 200 N was required toreduce the pelvis sufficiently, i.e., symphysis gap of less than 10 mm.

[0048]FIG. 14 shows four CT images of a fractured pelvis. FIGS. A and Bshow the fractured pelvis prior to sling-induced reduction. The pelvicring disruption is apparent by a widened SI joint in image (A) and asymphysis gap of 50 mm (B). As shown in images C and D, sling tension atthe acetabular level at a tension of 200 N resulted not only in the mostefficient translation of the applied sling tension into pelvicreduction, but also yielded the best quality in reduction.

[0049] Although the invention has been disclosed in its preferred forms,the specific embodiments thereof as disclosed and illustrated herein arenot to be considered in a limiting sense, because numerous variationsare possible. As used herein, singular terms do not preclude the use ofmore than one of the associated element, and embodiments using more thanone of a particular element are within the spirit and scope of theinvention. Applicants regard the subject matter of their invention toinclude all novel and nonobvious combinations and subcombinations of thevarious elements, features, functions, and/or properties disclosedherein. No single feature, function, element or property of thedisclosed embodiments is essential. The following claims define certaincombinations and subcombinations of features, functions, elements,and/or properties that are regarded as novel and nonobvious. Othercombinations and subcombinations may be claimed through amendment of thepresent claims or presentation of new claims in this or a relatedapplication. Such claims, whether they are broader, narrower, equal, ordifferent in scope to the original claims, also are regarded as includedwithin the subject matter of applicants' invention.

We claim:
 1. A method of stabilizing a fractured pelvis comprisingsecuring a belt around a person's fractured pelvis, and automaticallysetting the belt at a tension level that has been predetermined tosubstantially reduce a fractured pelvis without excessive compression.2. The method of claim 1 , wherein the setting step includes the step ofoperating a buckle device that automatically establishes an appropriatecircumference for the belt when the tension on the belt is in the rangeof approximately 150 N to 250 N.
 3. The method of claim 2 furthercomprising the step of conducting x-ray analysis through the belt toacquire information about the fracture.
 4. The method of claim 2 ,wherein the securing step includes the step of securing the beltsymmetrically by pulling on opposite end portions of the beltsimultaneously, thereby stabilizing the fractured pelvis evenly.
 5. Amethod of securing a pelvic fixator comprising temporarily reducing afractured pelvis by tightening a belt device around a person's pelvis,and securing a pelvic fixator while the belt is secured around theperson's pelvis.
 6. The method of claim 5 further comprising the step ofautomatically setting an appropriate tension on the belt by providing abuckle that locks and maintains a circumference for the belt when thetension is in the range of approximately 150 N to 250 N.
 7. A method ofreducing a pelvic fracture comprising applying circumferential externaldistributed pressure around a person's pelvis by securing a belt havinga tension in the range of approximately 150 N to 250 N.
 8. The method ofclaim 7 further comprising the step of transporting the person to ahospital.
 9. A method of stabilizing a fractured pelvis in an emergencysituation comprising securing a sling member around a person's fracturedpelvis, and tightening a sling member by operating a buckle mechanismthat exhibits a hysteresis effect between the minimal force required tolock the buckle and the maximal force required to unlock the buckle.